Plant Oils

Cold Pressing:

• Seeds are combined using a combine harvester
• Seeds are taken to a factory & crushed
• Crushed seeds are pressed to extract the oil
• The impurities are removed & the oil is processed
• This makes food oils

Distillation:

• Plant parts are put into boiling water
• The oil from the plants evaporates along with the steam
• The vapour is condensed & collected
• Water & impurities are removed
• This makes essential oils ( for perfumes)

Vegetable oils are useful for cooking because of their high boiling point

Foods cooked in oil instead of water have more fat = a higher energy content

However, they can cause heart disease & other problems

Vegetable oils can be hardened to make them solids at room temperature- eg. butter:

• The oil is reacted with hydrogen in a nickel catalyst at 60 degrees
• One c=c double bond breaks & hydrogen is added to the broken ends of the bonds
• Not all the c=c bonds are hydrogenated
• The unsaturated oil becomes saturated
• This is called Hydrogenation

Saturated fats:

• No c=c double bonds
• Very unhealthy

Unsaturated fats:

• One or more c=c double bond in its molecules
• Healthier than saturated fats

Monounsaturated fats:

• One c=c double bond per molecule

Polyunsaturated fats:

• More than one c=c double bond per molecule

Unsaturated:

• Contains double bonds
• Low melting point
• Molecules dont fit well together
• Attractions between the molecules are weak
• The fat/ oil is a liquid

Saturated:

• No double bonds
• High melting point
• Molecules fit together well
• Attraction between molecules is strong
• The fat/ oil is solid

Emulsifiers

• Mixes two liquids together that dont usually mix-eg. oil & water
• The molecules in emulsifiers have two parts, one that is attracted to the oil, one that is attracted to the water
• Hydrophillic - water loving (attracted to water)
• Hydrophobic - water fearing (attracted to oil)

Some emulsions include:

• Margarine
• Ice cream
• Bread

Immiscible: Don't mix